Human progenitor cells are the immature cells that give rise to all of the different types of mature cells that make up the organs and tissues of the adult body. The transition from progenitor cell to mature, specialised adult cell is via a process called differentiation.
Progenitor cells in the body take different pathways of differentiation in response to different stimuli from their environment. Similarly, progenitor cells in the laboratory can be stimulated to differentiate along different pathways by exposing them to various combinations of biochemicals. With appropriate stimuli, progenitor cells can differentiate into, among other tissues, blood cells, bone, cartilage, fat, blood vessels or heart muscle. Because of this, great interest is given to the use of progenitor cells as the basis of treatments to repair and re-grow of a range of tissues and organs.
Progenitor cells exist in the embryo and also in adult tissues such as bone marrow, fat, skin and dental pulp, though in much smaller relative numbers than in the embryo. The two types of adult progenitor cells are haematopoietic, which give rise to new bone marrow and blood cells, and non-haematopoietic, which give rise to solid organs and tissues, such as bone, heart and cartilage. Haematopoietic-type adult progenitor cells can be readily obtained from bone marrow and are already being used clinically. However, technology related to non-haematopoietic-type adult progenitor cells is much less developed due to the difficulty of obtaining sufficient numbers of these cells and of growing them in the laboratory.
In order to use progenitor cells in therapy it is necessary to be able to successfully store the progenitor cells prior to their use. The progenitor cells must be stored in such a way that they are effectively preserved and their viability is maintained. In general, the progenitor cells are cryopreserved for storage and thawed prior to use.
Cryogenic preservation (storage below −100° C.) of cell cultures is widely used to maintain backups or reserves of cells without the associated effort and expense of feeding and caring for them. The success of the freezing process depends on four critical areas, proper handling of the cultures, controlled freezing, proper storage and an appropriate cryoprotective agent. The last point is particularly important and a suitable agent can assist in maintaining the viability of the cells.
In a clinical setting, it is particularly important that following cryopreservation, the cells remain viable and any increase in the viability of the cells will boost the effect of the treatment.
In addition, in order for the progenitor cells to be therapeutically effective it is necessary for them to differentiate into the required cell type. Thus, there is also a need to develop effective regulators of progenitor cell differentiation to ensure that the progenitor cells differentiate into the required cell type.
Furthermore, there is also a need to develop effective regulators of progenitor cell proliferation. It is often desirable for the progenitor cells to proliferate both in vitro and in vivo.
Therefore, there remains a need for agent(s) which can protect the progenitor cells during cryopreservation, enhance their viability, regulate their differentiation and/or regulate their proliferation.